/Engine/Plugins/Animation/MLDeformer/MLDeformerFramework/Source/MLDeformerFrameworkEditor/Public/MLDeformerMorphModelEditorModel.h
Add any required bone to the mask. For example when we have finger bones that are not included in the bone inputs to the ML model, we still have to add those to the mask of the closest bone that is included (likely the hand or lower arm). With closest we mean the closest up the hierarchy chain (traversing to the parent and the parent's parent, etc). We call those virtual parents in this context.
void AddRequiredBones ( const [FReferenceSkeleton](API\Runtime\Engine\FReferenceSkeleton) & RefSkel, int32 SkeletonBoneIndex, const [TArray](API\Runtime\Core\Containers\TArray)< int32 > & VirtualParentTable, [TArray](API\Runtime\Core\Containers\TArray)< int32 > & OutBonesAdded )